MRI Nerve Enhancement-struggling to get proper help

Nerve root enhancement on lumbar MRI — what should the workup look like?

A young adult in my extended family has had loss of bladder function for several months. During an attempted urodynamics test, they had no sensation of the bladder filling, so it couldn't be finished. An ER visit last month included a contrast MRI that showed enhancement of the cauda equina nerve roots — but the discharge blamed everything on constipation, and a month later nothing has improved.

No lumbar puncture, no bloodwork for inflammatory or infectious causes, no follow-up neurology exam. Between a monthslong PCP waitlist and a dismissive specialist, nobody has taken ownership of the finding.

For those who've dealt with enhancing nerve roots (arachnoiditis, CIDP, sarcoid, infection, etc.):

1. What tests actually led to your diagnosis, and in what order? Should a spinal tap be the first ask?
2. How did you get a neurology department to accept the case when the ER and local specialists had already brushed it off?
3. Does absent bladder sensation point toward anything specific in your experience?

Grateful for any direction — they just need someone to actually investigate this.